Question

Write a function to create a copy of a string with the prototype below. (C Language)

char * strcpy (const char *);

The function should dynamically allocate the necessary memory for the new string. You can do that with

char * newstr = (char *) malloc(sizeof(char) * (strlen(str)+1));

assuming str is your input string. Think though how you would copy the characters of the string, and don't forget about the end of string character.

Answer 1

#include <stdio.h>
#include <stdlib.h>

char *strcpy(const char *);

int main() {
    char *s = strcpy("Hello");
    printf("%s\n", s);
    free(s);
    return 0;
}

char *strcpy(const char *str) {
    int len = 0, index = 0;
    char *result;
    while (str[len]) ++len;
    result = (char *) malloc(sizeof(char) * (len + 1));
    while (str[index]) {
        result[index] = str[index];
        ++index;
    }
    result[index] = '\0';
    return result;
}